Molecular Orbital Theory for Transition Metal Complexes

Using ligand field theory (MO approach), explain why CO is a much stronger field ligand than H2O in the spectrochemical series. (a) Draw the relevant MO interactions for both ligands with a transition metal. (b) Explain the role of π-backbonding. (c) How does this affect the magnitude of Δo? (d) Predict the effect on the CO stretching frequency when CO coordinates to a metal with many d-electrons versus few d-electrons.